1. Technical Field
The present invention relates to a terahertz wave detection device, a terahertz wavelength filter, an imaging device, and a measurement device.
2. Related Art
Recently, terahertz waves have gained attention. Terahertz waves are electromagnetic waves having frequencies equal to or greater than 100 GHz and equal to or less than 30 THz. Terahertz waves may be used, for example, for imaging, various measurements such as spectroscopy, nondestructive inspection, and the like.
A terahertz wave detector that detects terahertz waves may be a pyroelectric sensor or a bolometer. A major feature of both these detectors may be high sensitivity to terahertz waves. Further, a large and cumbersome optical delay mechanism such as a THz-TDS (Time-Domain Spectrometry) spectrophotometer is unnecessary.
However, since a pyroelectric sensor or a bolometer only detects the presence or absence of terahertz waves via a change in the quantity of heat from the device, it is not possible to detect the frequency spectrum of the terahertz waves. Further, to perform spectrum detection, a wavelength filter that selectively transmits terahertz waves having a predetermined wavelength that is desired to be detected becomes necessary.
A wavelength filter that transmits terahertz waves having a predetermined wavelength has been proposed (for example, see International Publication WO. 08/75624). This wavelength filter includes a substrate, and a metal film installed on the substrate. The metal film has a plurality of holes. By combining this wavelength filter and the pyroelectric sensor or the bolometer, only terahertz waves having a predetermined wavelength are detected.
However, if such a wavelength filter is designed for the terahertz wavelength band, the pitch of the holes is increased, and thus the area of the wavelength filter becomes too large.